The present invention relates to determining radiation dosage. In particular, radiation dosage associated with medical therapy or imaging is determined.
Medical imaging or therapy systems may generate radiation. For example, x-ray systems, computed tomography systems or x-ray therapeutic systems generate radiation. A linear accelerator generates x-ray photons. The dosage of x-ray photons supplied to a patient is regulated or limited. A detector is positioned to determine a dosage of x-ray photons applied to the patient. For example, a detector is positioned between the linear accelerator and a patient area for determining the dose of radiation output by the linear accelerator.
Radiation may impact on other components within the systems, such as circuit boards. The linear accelerator control system connects with the dose detector. The circuit board for the control system may be within a radiation environment. Most of the radiation produced by the accelerator is directed at the patient, but a certain amount of radiation is emitted in random directions, and it is not practical to shield all the radiation. The extra radiation, if it impinges on circuits and circuit boards, may cause the circuits or circuit boards to deteriorate over the life of the medical system.
Individual circuit boards may be replaced at various times for various reasons. Typically, the reasons are unrelated to radiation exposure. A service engineer removes the board and returns the board to a manufacturer. The returned boards are evaluated, possibly repaired, and then returned to the stock of replacement parts. However, it is difficult to predict when a subsequent failure may occur. The uncertainly is expensive. If all returned boards were discarded, then valuable boards with substantial life may be unnecessarily discarded. If all working circuit boards were returned, then service problems may be generated by circuit boards with minimal remaining useful life.